After the discovery of the structure of DNA in 1953, scientists working in molecular biology embraced reductionism—the theory that all complex systems can be understood in terms of their components. Reductionism, however, has been widely resisted by both nonmolecular biologists and scientists working outside the field of biology. Many of these antireductionists, nevertheless, embrace the notion of physicalism—the idea that all biological processes are physical in nature. How, Alexander Rosenberg asks, can these self-proclaimed physicalists also be antireductionists?

With clarity and wit, Darwinian Reductionism navigates this difficult and seemingly intractable dualism with convincing analysis and timely evidence. In the spirit of the few distinguished biologists who accept reductionism—E. O. Wilson, Francis Crick, Jacques Monod, James Watson, and Richard Dawkins—Rosenberg provides a philosophically sophisticated defense of reductionism and applies it to molecular developmental biology and the theory of natural selection, ultimately proving that the physicalist must also be a reductionist.

Economics today cannot predict the likely outcome of specific events any better than it could in the time of Adam Smith. This is Alexander Rosenberg's controversial challenge to the scientific status of economics. Rosenberg explains that the defining characteristic of any science is predictive improvability—the capacity to create more precise forecasts by evaluating the success of earlier predictions—and he forcefully argues that because economics has not been able to increase its predictive power for over two centuries, it is not a science.

Do the sciences aim to uncover the structure of nature, or are they ultimately a practical means of controlling our environment?

In Instrumental Biology, or the Disunity of Science, Alexander Rosenberg argues that while physics and chemistry can develop laws that reveal the structure of natural phenomena, biology is fated to be a practical, instrumental discipline. Because of the complexity produced by natural selection, and because of the limits on human cognition, scientists are prevented from uncovering the basic structure of biological phenomena. Consequently, biology and all of the disciplines that rest upon it—psychology and the other human sciences—must aim at most to provide practical tools for coping with the natural world rather than a complete theoretical understanding of it.

Rosenberg applies current thinking in philosophy of science to neoclassical economics in order to assess its claims to scientific standing. Although philosophers have used history and psychology as paradigms for the examination of social science, there is good reason to believe that economics is a more appropriate subject for analysis: it is the most systematized and quantified of the social sciences; its practitioners have reached a measure of consensus on important aspects of their subject; and it encompasses a large number of apparently law-like propositions.